Anyway, this thread reminds me of the saying "If you don't think representation matters, you're probably well represented".
I thought it worked well for the Malory Towers adaptation. I also find nothing particularly nostalgic about Blyton's representation of ethnic minorities, or even people who were not from England. The xenophobia is very evident in her representation of the gormless French teachers, who are always the ones to be completely taken in by every insipid, predictable 'treek'. The (implicitly more sensible) English mistresses see through the high jinks immediately, and in typically po-faced style swiftly administer the appropriate punishments.
As for Americans, their girls grow up too quickly and it's down to the English girls to teach them that being a child, and concerning themselves less with their clothes, nails and the cinema, is the 'appropriate' model of behaviour. In other words, squash them into swift conformity, and extinguish any hint of individuality.
The worst portrayal of an American was that of the thieving Mr Henning in 'Five on Finniston Farm', not to mention his ghastly son, Junior.
It's not accidental that the very worst and most ruthless of Blyton's usually cardboard-cutout, Scooby Doo style villains was the murderous Jo Jo, a black 'servant'. It might be prudent to point out that the rest of the baddies were white, but this man is an unusually nasty piece of work for Blyton, and practically every other mention of him also makes mention of the colour of his skin. This character has been updated to omit these details in the later publication. I'm glad to see it: I don't necessarily discourage my DC from reading Blyton - although we do discuss the shortcomings of her worldview - but I would not want him reading naked prejudice like this.
(On a lighter note I am, however, cackling at the horrific yet infinitely entertaining image of Bill Smugs as a furry .....)